Image forming method, image formng apparatus, intermediate transfer body, method of modifying surface of intermediate transfer body

Abstract

The invention allows an image printing on a wide range of print media regardless of how much ink the print media absorb, without sacrificing a high printing flexibility of an ink jet printing system. To this end, the image forming method of this invention includes: a process of modifying a surface of an intermediate transfer body by applying energy to the surface; a process of ejecting ink onto the surface-modified intermediate transfer body by using an ink jet printing device; and a process of transferring ink from the intermediate transfer body to a print medium. With this invention, therefore, an ink image can be formed on the intermediate transfer body having a surface layer, without causing bleeding or beading, and then transferred onto the print medium in good condition.

Description

TECHNICAL FIELD [0001] The present invention relates to an image forming method and an image forming apparatus both using an ink jet printing system, an intermediate transfer body used in the image forming method and a method of modifying a surface of the intermediate transfer body. More particularly the present invention relates to an image forming method and an image forming apparatus, both of which use an intermediate transfer body in forming an image on a print medium in order to make it unlikely for an image quality to be affected by the amount of ink absorbed in the print medium, an intermediate transfer body used in the image forming method and a method of modifying a surface of the intermediate transfer body. BACKGROUND ART [0002] A mainstream image forming method using paper as print media is currently an offset printing. The offset printing is a technique suited for mass printing. That is, a printing plate for an image is fabricated and set in a printing machine to make co...

AI Technical Summary

Benefits of technology

[0014] As can be seen from the above, in the ink jet printing system the use of an intermediate transfer body is advantageous in enhancing a level of freedom in the selection of print media. However, even the system employing the intermediate transfer body still has room for improvement to make a transferred ink image on the print medium high in quality.

Problems solved by technology

Disadvantages of the offset printing, such as time and cost required by a printing plate production process and a vast investment needed to purchase the printing machine, have little adverse effect on the cost per printed sheet and speed because the printed matter is produced in large quantities.

As a trend is gaining momentum in recent years for information versatility and more and more diversified printed matters are printed in small quantities, a problem has surfaced that the production cost of printing plates for individual printed matters becomes relatively high.

Since the current offset printing has a long lead time, from a text preparation to a printing plate production and a printing familiarization (stabilizing of a printing machine), the production period cannot be shortened even when the number of printed copies is small.

Further, since a huge facility investment is necessary and all processes require high levels of skills, production locations are limited, which means it takes time for printed matters to be delivered to customers.

Among points in which printed matters produced by the ink jet printing are inferior to offset-printed matters are a glossiness of printed matter, a printability on thin paper, a printability on both sides of paper and a printing cost.

If printing is done on paper with a small ink absorption capability, ink may remain on the surface without being fully absorbed in paper, which may cause undesired phenomena, such as a bleeding in which the remaining ink becomes mixed with adjoining ink droplets and a beading in which previously landed ink droplets are drawn to subsequently landed ink droplets, resulting in a degradation of a printed image quality and a failure to dry properly.

Under these circumstances, it is very difficult to form an image on paper with a high level of surface smoothness using the ink jet printing system without causing these problems.

However, if a transfer body with a non-ink absorbing surface is simply used, an ink on the transfer body remains fluidized, making it difficult to hold an ink image on the transfer body in good condition.

That is, the use of the non-ink absorbing surface as the intermediate transfer body surface to enhance the transferability of an ink image from the intermediate transfer body makes it difficult to hold the ink image on the intermediate transfer body in good condition.

Conversely, if the surface of the transfer body is made a surface that has a high ink absorbing capability to enhance the ability to hold the ink image on the intermediate transfer body, it becomes difficult to keep a good transferability of the ink image from the intermediate transfer body.

Simply heating the transfer body, however, can lower the ink fluidity only to a small extent, resulting in an ink image instantly spreading on the transfer body.

That is, the ink image cannot be held in good condition on the transfer body, which in turn renders the ink image on a print medium after transfer unsatisfactory.

This method has a problem that heat of the transfer body may reach an ink jet head and dry ink ejection nozzles, causing ejection failures.

This method therefore has not yet been put to practical use.

In this case, however, since a thickness of affixed ink is large, an ink image formed on the print medium after transfer looks unnatural, making the quality of the image on the print medium after transfer less than satisfactory, similar to the method disclosed in Japanese Patent Application Laid-open No. 5-330035 (1993).

This melting process takes time and there are some limitations on the components of ink, leaving much to be desired.

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